Eric Pugh
added a comment - 06/Mar/12 10:13 I recently ran into this same problem when I moved from 10 to 60+ shards. With 60+ shards, I would get back frequent connection errors from various shards. Changing the default max connection per host to a larger number, like 2048 solved the problem. When debugging this, I saw that in Solr 4, the default value is much larger. Here is a link to the commit: http://svn.apache.org/viewvc/lucene/dev/trunk/solr/core/src/java/org/apache/solr/handler/component/HttpShardHandlerFactory.java?r1=1291530&r2=1292353&diff_format=h . I don't know if this needs to be configurable, or just bumped up to a larger number, like the 256 value from Solr 4.